This invention relates to a magnetic disk device; and, more particularly, the invention relates to the structure of a magnetic head slider and to a magnetic disk in a contact recording magnetic disk device in which the magnetic head slider touches the magnetic disk.
To increase the recording density of a magnetic disk device, a narrowing of flying height, that is defined as the spacing between a magnetic head slider mounted with a magnetic head and a rotating magnetic disk, is important. A uniform flying height over the entire surface of the magnetic disk is also required. Further, any fluctuation of flying height due to environmental changes, especially a decrease of the flying height due to a drop in atmospheric pressure when operating at a high altitude, is required to be minimized. In proportion to a decrease in the flying height, the possibility of contact by the magnetic head slider with the magnetic disk increases; and, if the degree of contact is severe, the magnetic head slider crashes against the magnetic disk and there is a possibility of destroying the recorded data on the magnetic disk.
A technique for generally equalizing the flying height over the entire surface of the magnetic disk, for reducing a decrease of the flying height and for keeping a uniform flying height all over the magnetic disk when the disk is used at a high altitude, is disclosed by JP-A-2000-57724. This Japanese publication discloses a step air bearing sub-ambient pressure force magnetic head slider which generally equalizes the flying height over the entire surface of the magnetic disk and makes it possible to reduce a decrease of the flying height when the disk is used at a high altitude by the adequate combination of the rail surfaces with a step air bearing having a recess with a depth of sub-microns, the recess being deeper than that of the air bearing, for generating a sub-ambient pressure force.